Gas turbine power generator having humidifying and cooling means

ABSTRACT

An object of the present invention is to provide a gas turbine power generator capable of increasing the power generation efficiency in partial load operation and decreasing a variation in the number of rotations caused by a variation in power generation load. The gas turbine power generator comprises a compressor ( 2 ) for compressing air, a combustor ( 5 ) for burning the compressed air and fuel, a turbine ( 6 ) driven by combustion gas produced in the combustor and driving the compressor ( 2 ) and a generator ( 7 ), a regenerative heat exchanger ( 4 ) for exchanging heat between exhaust gas from the turbine and the compressed air led into the combustor, an intake air sprayer ( 1 ), and a humidifier ( 3 ). Intake air flown into the regenerative heat exchanger ( 4 ) is humidified and cooled by the intake air sprayer ( 1 ) and the humidifier ( 3 ).

TECHNICAL FIELD

The present invention relates to a gas turbine power generator, and moreparticularly to a gas turbine power generator suitable for the case ofemploying a regenerative heat exchanger in the power generator.

BACKGROUND ART

Recently, as an independent power plant with capacity of from severaltens to several hundreds kilowatts, a gas turbine power generator hasbeen studied which employs a gas turbine to operate a generator andwhich includes a regenerative heat exchanger. In such a gas turbinepower generator, the number of rotations N and a fuel flow rate M_(F)are adjusted to hold the number of rotations N at a minimum in the rangesatisfying a demanded load while referring to a turbine outlettemperature T_(OT) and a regenerative heat exchanger outlet temperatureT_(RO), thereby holding the combustion temperature as high as possibleand increasing the efficiency of power generation.

DISCLOSURE OF THE INVENTION

In the gas turbine power generator described above, however, when an airflow rate M_(A) reduces with a decrease of the power generation output,a thermal drop in a turbine is reduced and the turbine outlettemperature T_(OT) reaches a turbine outlet setting temperature T_(OTT)prior to the regenerative heat exchanger outlet temperature T_(RO).Hence, the regenerative heat exchanger outlet temperature T_(RO) cannotbe held at a sufficiently high value, thus resulting in a problem thatthe regenerative heat exchange amount cannot be ensured at a sufficientlevel and the efficiency of power generation under a partial load isreduced.

Also, when a load variation occurs frequently, the frequency of avariation in the number of rotations caused by the load variation isincreased, and the operation of increasing and decreasing the number ofrotations N is repeated until the turbine outlet temperature T_(OT) willbe equal to the turbine outlet setting temperature T_(OTT) or theregenerative heat exchanger outlet temperature T_(RO) will be equal toor higher than a regenerative-heat-exchanger outlet setting temperatureT_(ROT). This leads to another problem that high-cycle thermal fatiguecaused by a variation in the number of rotations of the turbine isnoticeable.

An object of the present invention is to provide a gas turbine powergenerator capable of increasing the power generation efficiency inpartial load operation and decreasing a variation in the number ofrotations caused by a variation in power generation load.

To achieve the above object, the present invention provides a gasturbine power generator comprising a compressor for compressing air; acombustor for burning the compressed air and fuel; a turbine driven bycombustion gas produced in the combustor and driving the compressor anda generator; and a regenerative heat exchanger for exchanging heatbetween exhaust gas from the turbine and the compressed air led into thecombustor, wherein the gas turbine power generator further compriseshumidifying and cooling means for humidifying and cooling intake airflown into the regenerative heat exchanger. With that construction, byhumidifying and cooling the intake air supplied to the combustor, it ispossible to increase the power generation efficiency in partial loadoperation and to decrease a variation in the number of rotations causedby a variation in power generation load.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a system diagram showing an overall construction of a gasturbine power generator according to a first embodiment of the presentinvention.

FIG. 2 is a flowchart showing a method of operating the gas turbinepower generator according to the first embodiment of the presentinvention.

FIG. 3 is a flowchart showing the method of operating the gas turbinepower generator according to the first embodiment of the presentinvention.

FIG. 4 is a flowchart showing the method of operating the gas turbinepower generator according to the first embodiment of the presentinvention.

FIG. 5 is a flowchart showing control procedures of an interlock controlsequence for use in the method of operating the gas turbine powergenerator according to the first embodiment of the present invention.

FIG. 6 is an explanatory graph showing turbine inlet and outlettemperatures and regenerative heat exchanger inlet and outlettemperatures with respect to a power generation load in the gas turbinepower generator according to the first embodiment of the presentinvention.

FIG. 7 is an explanatory graph showing a regenerative heat exchangeamount with respect to a power generation load in the gas turbine powergenerator according to the first embodiment of the present invention.

FIG. 8 is an explanatory graph showing power generation efficiency withrespect to a power generation load in the gas turbine power generatoraccording to the first embodiment of the present invention.

FIG. 9 is an explanatory graph showing the number of rotations withrespect to a power generation load in the gas turbine power generatoraccording to the first embodiment of the present invention.

FIG. 10 is a flowchart showing a method of operating a gas turbine powergenerator according to a second embodiment of the present invention.

FIG. 11 is a flowchart showing a method of operating a gas turbine powergenerator according to a third embodiment of the present invention.

FIG. 12 is an explanatory graph showing a temperature distribution in aregenerative heat exchanger resulting when a flow rate Mw of humidifyingwater is changed in five ways in the gas turbine power generatoraccording to the third embodiment of the present invention.

FIG. 13 is an enlarged graph of a portion of FIG. 12.

FIG. 14 is a system diagram showing an overall construction of a gasturbine power generator according to a fourth embodiment of the presentinvention.

FIG. 15 is a system diagram showing an overall construction of a gasturbine power generator according to a fifth embodiment of the presentinvention.

FIG. 16 is a system diagram showing an overall construction of a gasturbine power generator according to a sixth embodiment of the presentinvention.

FIG. 17 is a flowchart showing a method of operating the gas turbinepower generator according to the sixth embodiment of the presentinvention.

BEST MODE FOR CARRYING OUT THE INVENTION

The construction and operation of a gas turbine power generatoraccording to a first embodiment of the present invention will bedescribed below with reference to FIGS. 1 to 7.

A description is first made of overall construction of the gas turbinepower generator according to this embodiment with reference to FIG. 1.

The gas turbine power generator according to this embodiment primarilycomprises an intake air sprayer 1, a compressor 2, a humidifier 3, aregenerative heat exchanger 4, a combustor 5, a turbine 6, a generator7, a rectifier 8, a capacitor 9, an inverter 10, an output transformer11, a supply water treating unit 12, a waste heat recovering unit 13,and a control unit 100. The gas turbine power generator of thisembodiment is particularly featured in including working fluidhumidifying means, such as the intake air sprayer 1 and the humidifier3, and associated accessory equipment, such as the supply water treatingunit 12. The control unit 100 executes not only control executed in aknown gas turbine power generator, but also control of the working fluidhumidifying means, such as the intake air sprayer 1 and the humidifier3.

The intake air sprayer 1 is disposed on the inlet side of the compressor2 and is capable of humidifying and cooling sucked air 21 with a waterspray depending on the ambient environment and the operation state. Onthe inlet side of the intake air sprayer 1, there are disposed anambient air temperature means 41 for detecting an ambient airtemperature around the sucked air 21, an atmosphere pressure measuringmeans 51 for detecting an atmosphere pressure around the sucked air 21,and a flow rate measuring means 14 for measuring a flow rate of thesucked air 21. A compressor inlet differential-pressure measuring means59 disposed in association with the flow rate measuring means 14measures a differential pressure at an inlet of the compressor. Valuesmeasured by the ambient air temperature measuring means 41, theatmosphere pressure measuring means 51, the flow rate measuring means14, and the compressor inlet differential-pressure measuring means 59are taken into the control unit 100.

The air 21 sucked into the inlet side of the compressor 2 is humidifiedand cooled by the intake air sprayer 1. Treated supply water 24 issupplied to the intake air sprayer 1 from the supply water treating unit12. The supply water treating unit 12 carries out treatment of water 23supplied to it, such as dust removal and softening. The treated supplywater 24 is pressurized by an intake-air cooling water ejection pump 34,and its flow rate is adjusted by an intake-air cooling water flowadjusting valve 35. Then, the treated supply water 24 turns tointake-air spraying water 25 to humidify the sucked air 21 in the intakeair sprayer 1. The intake-air cooling water flow adjusting valve 35 iscontrolled by the control unit 100. The amount of water 28 drained fromthe intake air sprayer 1 is measured by a drained-water flow measuringmeans 60 and discharged through a drained-water discharge valve 38.

The air humidified and cooled by the intake air sprayer 1 is compressedby the compressor 2 and introduced to the humidifier 3. On the inletside of the compressor 2, there are disposed a compressor inlettemperature measuring means 42 for measuring an inlet temperature of thecompressor and a compressor inlet pressure measuring means 52 formeasuring an inlet pressure of the compressor. Also, on the deliveryside of the compressor 2, there are disposed a compressor deliverytemperature measuring means 43 for measuring a delivery temperature ofthe compressor and a compressor delivery pressure measuring means 53 formeasuring a delivery pressure of the compressor. Values measured by thecompressor inlet temperature measuring means 42, the compressor inletpressure measuring means 52, the compressor delivery temperaturemeasuring means 43, and the compressor delivery pressure measuring means53 are taken into the control unit 100.

The humidifier 3 is able to humidify the intake air by ejecting arequired amount of water, warm water or water vapor depending on theoperation state, such as a power demand. The treated supply water 24having been treated by the supply water treating unit 12 is pressurizedby a humidifying water ejection pump 36 and its flow rate is adjusted bya humidifying water flow adjusting valve 37. Then, the treated supplywater 24 turns to humidifying water 26 to humidify the intake air in thehumidifier 3. The humidifying water flow adjusting valve 37 iscontrolled by the control unit 100.

The intake air having flown out of the humidifier 3 is preheated in theregenerative heat exchanger 4 by heat recovered from exhaust dischargedfrom the turbine 6. On the inlet side of the regenerative heat exchanger4, there are disposed an inlet temperature measuring means 44 formeasuring an inlet temperature of the regenerative heat exchanger and aregenerative-heat-exchanger inlet pressure measuring means 54 formeasuring an inlet pressure of the regenerative heat exchanger. Also, onthe outlet side of the regenerative heat exchanger 4, there are disposeda regenerative-heat-exchanger outlet temperature measuring means 46 formeasuring an outlet temperature of the regenerative heat exchanger and aregenerative-heat-exchanger outlet pressure measuring means 55 formeasuring an outlet pressure of the regenerative heat exchanger. Valuesmeasured by the regenerative-heat-exchanger inlet temperature measuringmeans 44, the regenerative-heat-exchanger inlet pressure measuring means54, the regenerative-heat-exchanger outlet temperature measuring means46, and the regenerative-heat-exchanger outlet pressure measuring means55 are taken into the control unit 100.

The combustor 5 mixes and burns the intake air preheated by theregenerative heat exchanger 4 and fuel 22 introduced at a flow rateadjusted by a fuel flow adjusting valve 32. High-temperature gasresulting from the combustion flows into the turbine 6. A fuel cutoffvalve 31 for cutting off fuel supply is disposed downstream of the fuelflow adjusting valve 32. The fuel cutoff valve 31 and the fuel flowadjusting valve 32 are controlled by the control unit 100.

In the turbine 6, the high-temperature gas supplied from the combustor 5is expanded to perform work and produces power. The compressor 2 and thegenerator 7 are driven with the produced power. On the inlet side of theturbine 6, there are disposed an inlet temperature measuring means 47for measuring an inlet temperature of the turbine and a turbine inletpressure measuring means 56 for measuring an inlet pressure of theturbine. Also, on the outlet side of the turbine 6, there are disposed aturbine outlet temperature measuring means 48 for measuring an outlettemperature of the turbine and a turbine outlet pressure measuring means57 for measuring an outlet pressure of the turbine. Values measured bythe turbine inlet temperature measuring means 47, the turbine inletpressure measuring means 56, the turbine outlet temperature measuringmeans 48, and the turbine outlet pressure measuring means 57 are takeninto the control unit 100.

Electric power generated from the generator 7 driven by the turbine 6 isrectified by the rectifier 8 and its frequency is converted by theinverter 10 into a desired one depending on a customer. The electricpower is then supplied to a load. At this time, a generator outputvoltage is converted by the output transformer 11 as required. Theoutput voltage and current of the generator 7 are measured respectivelyby a generator output voltage measuring means 64 and a generator outputcurrent measuring means 65. A voltage between terminals of the capacitor9 is measured by a capacitor inter-terminal voltage measuring means 66.An output voltage of the output transformer 11 is measured by aload-terminal output voltage measuring means 63. An output current ismeasured by a load-terminal output current measuring means 62, and anoutput power is measured by a load-terminal output power measuring means61. Values measured by the generator output voltage measuring means 64,the generator output current measuring means 65, the capacitorinter-terminal voltage measuring means 66, the load-terminal outputvoltage measuring means 63, the load-terminal output current measuringmeans 62, and the load-terminal output power measuring means 61 aretaken into the control unit 100.

After recovery of heat in the regenerative heat exchanger 4, the exhaustfrom the turbine 6 is discharged as a gas-turbine exhaust gas 27 to theoutside of a plant. On the exhaust side of the regenerative heatexchanger 4, there are disposed an exhaust temperature measuring means49 for measuring a temperature of the exhaust gas 27 and an exhaustpressure measuring means 58 for measuring a pressure of the exhaust gas27. Values measured by the exhaust temperature measuring means 49 andthe exhaust pressure measuring means 58 are taken into the control unit100. As an alternative, the exhaust gas 27 may be introduced to a wasteheat recovering unit 13, such as a refrigerator or a boiler, for furtherrecovery of heat, and then finally discharged as the exhaust gas 27 fromthe waste heat recovering unit to the outside of the plant.

In the above arrangement, instead of the treated supply water 24, warmwater or water vapor obtained from the waste heat recovering unit 13 maybe supplied to the humidifier 3. Also, instead of the treated supplywater 24, cooled water obtained from the waste heat recovering unit 13may be supplied to the intake air sprayer 1. Additionally, the supplywater treating unit 12 is constructed to be adaptable for, in additionto externally supplied water, condensed water, etc. discharged andrecovered from, e.g., an air conditioner of the customer.

A method of operating the gas turbine power generator according to thisembodiment will be described below with reference to FIGS. 2 to 4.

FIGS. 2 to 4 are each a flowchart showing the method of operating thegas turbine power generator according to the first embodiment of thepresent invention. In control flows shown in those flowcharts, (A) inFIG. 2 continues to (A) in FIG. 3 and (B), (C) in FIG. 2 continuerespectively to (B), (C) in FIG. 4.

The method of operating the gas turbine power generator according tothis embodiment is processed and executed by the control unit 100, andis primarily made up of a load satisfaction loop s108, an optimizationloop s205, a misfire detection loop s123, and a burnout detection loops111. The load satisfaction loop s108, the optimization loop s205, andthe misfire detection loop s123 are executed in parallel at the sametime.

First, in step s101, the control unit 100 reads a load demand (demandedload power P_(D)).

Then, in step s102, the control unit 100 sets the number of rotations Ncorresponding to the demanded load by referring to a lookup table 103which stores memory data such as the number of rotations N correspondingto the demanded load. In parallel to the setting of the number ofrotations N in step s102, the load satisfaction loop s108 for continuingfuel supply at a flow rate satisfying the demanded load is executed,whereby the demanded load is always satisfied. Further, the optimizationloop s205 and the misfire detection loop s123 are executed in parallelso that the set number of rotations N is obtained. The number ofrotations N is adjusted by measuring an output of the generator outputvoltage measuring means 64 or an output of the capacitor inter-terminalvoltage measuring means 66, for example, which is in proportion to thenumber of rotations N, and by controlling the measured voltage.

The load satisfaction loop s108 is first described. The loadsatisfaction loop s108 is executed in parallel to the setting of thenumber of rotations N and functions to continue fuel supply at the fuelflow rate M_(F) satisfying the demanded load. By keeping the loadsatisfaction loop s108 under execution, the load demand 101 is alwayssatisfied.

In step s104, the control unit 100 determines the state of a loadterminal output power P_(GO) measured by the load-terminal output powermeasuring means 61. If the load terminal output power P_(GO) is largerthan the demanded load power P_(D) (P_(GO)>P_(D)), the control unit 100issues a command for decreasing the fuel flow rate M_(F) and controlsthe fuel flow adjusting valve 32 in step s105, thereby decreasing thefuel flow rate supplied to the combustor 5. If the load terminal outputpower P_(GO) is equal to the demanded load power P_(D) (P_(GO)=P_(D)),the control unit 100 issues a command for holding the fuel flow rateM_(F) and controls the fuel flow adjusting valve 32 in step s106,thereby holding the fuel flow rate supplied to the combustor 5. If theload terminal output power P_(GO) is smaller than the demanded loadpower P_(D) (P_(GO)<P_(D)), the control unit 100 issues a command forincreasing the fuel flow rate M_(F) and controls the fuel flow adjustingvalve 32 in step s107, thereby increasing the fuel flow rate supplied tothe combustor 5.

Thus, in the load satisfaction loop s108, the demanded load power P_(D)and the load terminal output power P_(GO) are compared with each other,and feedback control is performed so that both the powers coincide witheach other. To achieve more efficient operating conditions while alwayssatisfying the load demand with the load satisfaction loop s108, theoptimization loop s205 is executed in parallel.

The optimization loop s205 is now described. The optimization loop s205is a loop constructed based on the concept of keeping the combustiontemperature as high as possible and increasing the power generationefficiency by holding the number of rotations N at minimum within therange satisfying the demanded load while referring to a turbine outlettemperature T_(OT) and a regenerative heat exchanger outlet temperatureT_(RO).

The optimization loop s205 executes control such that, after setting aflow rate Mw of the humidifying water to a value resulting frommultiplying an air flow rate M_(A) by a constant α, the flow rate Mw ofthe humidifying water is gradually reduced to an optimum flow rate Mopwof the humidifying water. The air flow rate M_(A) is measured by theflow rate measuring unit 14. Alternatively, the air flow rate M_(A) maybe calculated from the temperature and pressure at the inlet of the gasturbine power generator, the number of rotations N, and a compressorperformance curve. Also, the constant α is decided, for example, bydividing a flow rate MwMin of the humidifying water in the minimum loadoperation within the range in which the flow rate Mw of the humidifyingwater is adjustable and combustion stability is not impaired, by the airflow rate M_(A) at that time. As an alternative, the constant α may becalculated from a maximum water vapor concentration at which combustionperformance, such as combustion stability and unburnt emissions, can beensured in the combustor 5.

In step s201, the control unit 100 sets, as the flow rate Mw of thehumidifying water, the value resulting from multiplying the air flowrate M_(A) by the constant α.

Then, in step s112, the control unit 100 remains standby until theoperation state will be steady.

Then, in step s113, the control unit 100 compares the turbine outlettemperature T_(OT) with the turbine outlet setting temperature T_(OTT).In this respect, the turbine outlet setting temperature T_(OTT) isdecided as follows. A turbine outlet maximum setting temperatureT_(OTTH) during the operation is determined from a turbine performancecurve by using the ambient air temperature and the atmosphere pressuremeasured respectively by the ambient air temperature measuring means 41and the atmosphere pressure measuring means 51 during the operation, theair flow rate M_(A) at the rated number of rotations N_(S), and a ratedturbine inlet temperature T_(ITS). A lower one of the turbine outletmaximum setting temperature T_(OTTH) and a regenerative heat exchangerallowable temperature T_(RMAX) is set as the turbine outlet settingtemperature T_(OTT). In a district where a variation in temperature ofopen air is small or in a district where an annual highest atmospherictemperature is relatively low, the turbine outlet maximum settingtemperature T_(OTTH) and a regenerative heat exchanger allowabletemperature T_(RMAX) decided using the above-described method at astandard ambient air temperature and atmosphere pressure can be set asthe turbine outlet setting temperature T_(OTT) and used thoroughly.Instead of comparing the turbine outlet temperature T_(OT) with theturbine outlet setting temperature T_(OTT), the turbine inlettemperature T_(IT) may be compared with a turbine inlet settingtemperature T_(ITT). Here, the turbine inlet setting temperature T_(ITT)means a maximum value of the turbine inlet temperature T_(IT) that isallowable for the turbine.

As a result of comparing the turbine outlet temperature T_(OT) with theturbine outlet setting temperature T_(OTT), if the turbine outlettemperature T_(OT) is higher than the turbine outlet setting temperatureT_(OTT) (T_(OT)>T_(OTT)), the control unit 100 issues an interlockcontrol start command in step s114. Interlock control is executed toavoid a trouble, such as burnout of the turbine 6 or the combustor 5,when the turbine outlet temperature T_(OT) is higher than the turbineoutlet setting temperature T_(OTT). Details of the interlock controlwill be described later with reference to FIG. 3.

If the turbine outlet temperature T_(OT) is equal to the turbine outletsetting temperature T_(OTT) (T_(OT)=T_(OTT)), the control unit 100issues a command for exiting the optimization loop in step s115. Then,in step s202, a command is issued to hold the flow rate Mw of thehumidifying water and the number of rotations N at the same values asthose set at that time. The load is thereby satisfied in step s117.

If the turbine outlet temperature T_(OT) is lower than the turbineoutlet setting temperature T_(OTT) (T_(OT)<T_(OTT)), the control unit100 compares the regenerative heat exchanger outlet temperature T_(RO)with the regenerative-heat-exchanger outlet setting temperature T_(ROT)in step s118.

As a result of comparing the regenerative heat exchanger outlettemperature T_(RO) with the regenerative-heat-exchanger outlet settingtemperature T_(ROT), if the regenerative heat exchanger outlettemperature T_(RO) is not lower than the regenerative-heat-exchangeroutlet setting temperature T_(ROT) (T_(RO)≧T_(ROT)), the control unit100 issues the command for exiting the optimization loop in step s115.Then, in step s202, the control unit 100 issues the command for holdingthe flow rate Mw of the humidifying water and the number of rotations Nat the same values as those set at that time.

If the regenerative heat exchanger outlet temperature T_(RO) is lowerthan the regenerative-heat-exchanger outlet setting temperature T_(ROT)in (T_(RO)<T_(ROT)), the control unit 100 compares the flow rate Mw ofthe humidifying water with the optimum flow rate MOpw of the humidifyingwater in step s203.

As a result of comparing the flow rate Mw of the humidifying water withthe optimum flow rate MOpw of the humidifying water, if the flow rate Mwof the humidifying water is larger than the optimum flow rate MOpw ofthe humidifying water (Mw>MOpw), the control unit 100 issues a commandfor decreasing the flow rate Mw of the humidifying water in step s204.When setting a decrease amount of the flow rate Mw of the humidifyingwater in this step, the decrease amount is set to, for example, theleast possible value within a flow rate adjustable range.

After decreasing the flow rate Mw of the humidifying water, the controlunit 100 remains standby in step s112 until the operation state will besteady, and then repeats in step s113 a sequence of control loop forcomparing again the turbine outlet temperature T_(OT) with the turbineoutlet setting temperature T_(OTT).

If the flow rate Mw of the humidifying water is not larger than theoptimum flow rate MOpw of the humidifying water (Mw≦MOpw), the controlunit 100 issues a command for decreasing the number of rotations N instep s119. When setting a decrease amount of the number of rotations Nin this step, a change amount of the number of rotations is set to, forexample, the minimum number of rotations that is significantlychangeable by means for controlling the number of rotations.

After decreasing the number of rotations N, the control unit 100 sets,in step s201, the flow rate Mw of the humidifying water to the valueresulting from multiplying the air flow rate M_(A) by the constant α.Subsequently, the control unit 100 remains standby in step s112 untilthe operation state will be steady, and then repeats in step s113 asequence of control loop for comparing again the turbine outlettemperature T_(OT) with the turbine outlet setting temperature T_(OTT).

Herein, the optimum flow rate MOpw of the humidifying water means theflow rate Mw of the humidifying water which is required for making theintake air temperature coincident with the saturation vapor temperatureat the inlet of the regenerative heat exchanger 4. The optimum flow rateMOpw of the humidifying water can be decided by measuring the pressureand temperature at the inlet of the regenerative heat exchanger 4 anddetermining a value of the optimum flow rate MOpw from a saturationtemperature formula. As an alternative, the saturation temperature maybe calculated in advance, and the optimum flow rate MOpw of thehumidifying water corresponding to required ranges of pressure andtemperature at the inlet of the regenerative heat exchanger 4 may bestored as memory data in a lookup table. Further, instead of measuringthe pressure and temperature at the inlet of the regenerative heatexchanger 4, the pressure and temperature at the inlet of theregenerative heat exchanger may be calculated by measuring the air flowrate and the pressure and temperature at the inlet of the compressor,and determining the compressor efficiency and compression ratio from ameasured value of the number of rotations N and a performance curveapproximation formula for the compressor. In addition, when deciding theoptimum flow rate MOpw of the humidifying water by the above-describedmethod, it is also possible to employ the pressure and temperature onthe delivery side of the compressor instead of the pressure andtemperature at the inlet of the regenerative heat exchanger.

In parallel to the load satisfaction loop s108 and the optimization loops120 described above, the temperature excessive rise (burnout) detectionloop s111 and the misfire detection loop s123 are always executed.

In the temperature excessive rise detection loop s111, the control unit100 compares, in step s109, the turbine outlet temperature T_(OT)measured by the turbine outlet temperature measuring means 48 with aturbine outlet upper-limit temperature T_(OTHL). If the turbine outlettemperature T_(OT) is not lower than the turbine outlet upper-limittemperature T_(OTHL), this means a large possibility of risk of deviceburnout. In step s110, therefore, the control unit 100 operates the fuelcutoff valve 31 at once to cut off the supply of the fuel 22 and to stopthe power generation. At this time, when the turbine outlet temperatureexceeds a predetermined alarm setting temperature, an alarm is issued toavoid the temperature of the turbine 6 from rising excessively. Thealarm setting temperature is set to a higher value depending on a riseof the open air temperature.

In the misfire detection loop s123, the control unit 100 determines thestate of the number of rotations N in step s121. If the number ofrotations N is not lower than the number of rotations N_(MIN) at thetime of ignition and is not higher than the number of rotations N_(MAX)at the time of maximum output (N_(MIN)≦N≦N_(MAX)), the control unit 100determines the turbine outlet temperature T_(OT) in step s122. If theturbine outlet temperature T_(OT) is not higher than a turbine outletlower-limit temperature T_(OTL) (T_(OT)≦T_(OTL)), the control unit 100operates, in step s110, the fuel cutoff valve 31 at once to cut off thesupply of the fuel 22 and to stop the power generation.

An interlock control sequence for use in the method of operating the gasturbine power generator according to this embodiment will be describedbelow with reference to FIG. 5.

FIG. 5 is a flowchart showing control procedures of the interlockcontrol sequence used in the method of operating the gas turbine powergenerator according to the first embodiment of the present invention.

In the interlock control sequence, if the turbine outlet temperatureT_(OT) is not lower than the turbine outlet upper-limit temperatureT_(OTHL), this means a large possibility of risk of device burnout.Therefore, the control unit operates the fuel cutoff valve 31 at once tocut off the supply of the fuel 22 and to stop the power generation.

When an interlock control start command is issued in step s114, thecontrol unit 100 compares, in step s206, the turbine outlet temperatureT_(OT) measured by the turbine outlet temperature measuring means 48with both a turbine outlet higher setting temperature T_(OTH) and theturbine outlet upper-limit temperature T_(OTHL).

If the turbine outlet temperature T_(OT) is not lower than the turbineoutlet upper-limit temperature T_(OTHL) (T_(OT)≧T_(OTHL)), this means alarge possibility of risk of device burnout. I step s110, therefore, thecontrol unit 100 operates the fuel cutoff valve 31 at once to cut offthe supply of the fuel 22 and to stop the power generation.

If the turbine outlet temperature T_(OT) is higher than the turbineoutlet setting temperature T_(OTT) and is lower than the turbine outlethigher setting temperature T_(OTH) (T_(OTT)<T_(OT)<T_(OTH)), the controlunit 100 issues, in step s202, the command for holding the flow rate Mwof the humidifying water and the number of rotations N at the samevalues as those set at that time.

If the turbine outlet temperature T_(OT) is not lower than the turbineoutlet higher setting temperature T_(OTH) and is lower than the turbineoutlet upper-limit temperature T_(OTHL) (T_(OTH)≦T_(OT)<T_(OTHL)), thecontrol unit 100 issues, in step s208, a command for increasing the flowrate Mw of the humidifying water so as to provide the operation statewith a lower possibility of risk. When setting an increase amount of theflow rate Mw of the humidifying water, the increase amount is preferablyset, for example, to be equal to the decrease amount of the flow rate Mwof the humidifying water, which is obtained with the command issued instep s204 for decreasing the flow rate Mw of the humidifying water.

After increasing the flow rate Mw of the humidifying water, the controlunit 100 remains standby in step s112 until the operation state will besteady, and then compares in step s207 the turbine outlet temperatureT_(OT) with each of the turbine outlet setting temperature T_(OTT), theturbine outlet higher setting temperature T_(OTH), the turbine outletupper-limit temperature T_(OTHL), and the turbine outlet lower-limittemperature T_(OTL).

As a comparison result, if the turbine outlet temperature T_(OT) is notlower than the turbine outlet upper-limit temperature T_(OTHL)(T_(OT)≧T_(OTHL)), this means a large possibility of risk of deviceburnout. In step s110, therefore, the control unit 100 operates the fuelcutoff valve 31 at once to cut off the supply of the fuel 22 and to stopthe power generation. Further, if the increase amount of the flow rateMw of the humidifying water is too large, there is a possibility ofmisfire. Accordingly, if the turbine outlet temperature T_(OT) is nothigher than the turbine outlet lower-limit temperature T_(OTL)(T_(OT)≦T_(OTL)), the control unit 100 also operates, in step s110, thefuel cutoff valve 31 at once to cut off the supply of the fuel 22 and tostop the power generation.

If the turbine outlet temperature T_(OT) is higher than the turbineoutlet setting temperature T_(OTT) and is lower than the turbine outlethigher setting temperature T_(OTH) (T_(OTT)<T_(OT)<T_(OTH)), the controlunit 100 issues, in step s202, the command for holding the flow rate Mwof the humidifying water and the number of rotations N at the samevalues as those set at that time.

If the turbine outlet temperature T_(OT) is still not lower than theturbine outlet higher setting temperature T_(OTH) and is lower than theturbine outlet upper-limit temperature T_(OTHL)(T_(OTH)≦T_(OT)<T_(OTHL)) , the control unit 100 issues, in step s208, acommand for increasing the flow rate Mw of the humidifying water againso as to provide the operation state with a lower possibility of risk.

If the turbine outlet temperature T_(OT) is higher than the turbineoutlet setting temperature T_(OTT) and is lower than the turbine outlethigher setting temperature T_(OTH) (T_(OTT)<T_(OT)<T_(OTH)), the controlunit 100 issues, in step s202, the command for holding the flow rate Mwof the humidifying water and the number of rotations N at the samevalues as those set at that time.

If the turbine outlet temperature T_(OT) is not higher than the turbineoutlet setting temperature T_(OTT) (T_(OT)≦T_(OTT)), the control unit100 issues, in step s127, a command for returning to the optimizationloop. Then, in step s113 of the optimization loop s205 shown in FIG. 2,the control unit 100 compares the turbine outlet temperature T_(OT) withthe turbine outlet setting temperature T_(OTT) for repeatedly executinga sequence of control loop.

With the gas turbine power generator according to this embodiment, asdescribed above, the power generation output and the power generationefficiency can be increased by applying a spray of intake air to a gasturbine and humidifying the intake air on the delivery side of thecompressor.

The power generation output and the power generation efficiency achievedwith the method of operating the gas turbine power generator accordingto this embodiment will be described below with reference to FIGS. 6 to9 in comparison with a known gas turbine power generator.

It is here assumed that the gas turbine power generator of thisembodiment and the known gas turbine power generator have the samepressure ratio, the turbine inlet temperature and the number ofrotations under rated conditions, and component units, such as aturbine, a compressor, a generator and a regenerative heat exchanger,have characteristics substantially identical to each other. However, thegas turbine power generator of this embodiment has a regenerative heatexchanger capacity and a turbine capacity both increased inconsideration of an increase in amount of a working fluid caused by thehumidification.

Also, the gas turbine power generator of this embodiment is a 100-kWclass gas turbine power generator designed to have a pressure ratio of3.5 and a turbine inlet temperature of 970° C. under the conditions ofan ambient air temperature of 15° C. and a relative humidity of 30%.Furthermore, in the gas turbine power generator of this embodiment, theair is always cooled at the compressor inlet with the intake air sprayer1 by using 0.2 weight percent of humidifying water with respect to theair mass flow rate.

With reference to FIG. 6, a description is first made of turbine inletand outlet temperatures and regenerative heat exchanger inlet and outlettemperatures with respect to a power generation load in the gas turbinepower generator of this embodiment in comparison with those in the knowngas turbine power generator.

FIG. 6 is an explanatory graph showing turbine inlet and outlettemperatures and regenerative heat exchanger inlet and outlettemperatures with respect to a power generation load in the gas turbinepower generator according to the first embodiment of the presentinvention. In FIG. 6, the vertical axis represents temperature and thehorizontal axis represents the power generation load normalized with therated load set to 100%.

In the gas turbine power generator of this embodiment, thehumidification on the delivery side of the compressor is not performedat the power generation load of not larger than 73% because the flowrate resulting from multiplying the air flow rate M_(A) by the constantα becomes lower than the controllable flow rate. In the range of powergeneration load from 73% to 90%, the humidification is performed at theoptimum flow rate MOpw of the humidifying water in accordance with theoperation control method shown in FIGS. 2 to 4. In the range of powergeneration load not lower than 90%, when the flow rate Mw of thehumidifying water is decreased in accordance with the optimization loopfrom the value resulting from multiplying the air flow rate M_(A) by theconstant α, the turbine outlet temperature T_(OT) reaches the turbineoutlet setting temperature T_(OTT) before the flow rate Mw of thehumidifying water reaches the optimum flow rate MOpw. Therefore, thehumidification is performed at a flow rate in excess of the optimum flowrate MOpw of the humidifying water.

A solid line A1 indicates the turbine inlet temperature with respect tothe power generation load in the gas turbine power generator of thisembodiment, and a solid line A2 indicates the turbine outlet temperaturewith respect to the power generation load in the gas turbine powergenerator of this embodiment. On the other hand, a broken line B1indicates the turbine inlet temperature with respect to the powergeneration load in the known gas turbine power generator, and a brokenline B2 indicates the turbine outlet temperature with respect to thepower generation load in the known gas turbine power generator.

At any power generation load, there is no significant difference in theturbine inlet and outlet temperature between the gas turbine powergenerator of this embodiment and the known gas turbine power generator.

A solid line A3 indicates the regenerative heat exchanger outlettemperature with respect to the power generation load in the gas turbinepower generator of this embodiment, and a broken line B3 indicates theregenerative heat exchanger outlet temperature with respect to the powergeneration load in the known gas turbine power generator. As seen fromthe comparing, with the operation control according to this embodiment,the regenerative heat exchanger outlet temperature can be consistentlyheld higher than that in the known gas turbine power generator.

Further, a solid line A4 indicates the regenerative heat exchanger inlettemperature with respect to the power generation load in the gas turbinepower generator of this embodiment, and a broken line B4 indicates theregenerative heat exchanger inlet temperature with respect to the powergeneration load in the known gas turbine power generator. As seen fromthe comparison, the regenerative heat exchanger outlet temperaturelowers in the range of power generation load not lower than 90% in whichthe flow rate Mw of the humidifying water exceeds the optimum flow rate,but it is still higher than the regenerative heat exchanger outlettemperature in the known gas turbine power generator.

In the range of power generation load not lower than 73% in which thehumidification is performed with the humidifier 3, the regenerative heatexchanger inlet temperature is reduced to a value substantiallycoincident with the saturation temperature at the regenerative heatexchanger inlet pressure by carrying out the operation control inaccordance with this embodiment. Thus, the temperature of turbineexhaust as a high-temperature side fluid flowing into the regenerativeheat exchanger is almost the same in both the gas turbine powergenerators of this embodiment and of the known type, and the temperatureof air delivered as a low-temperature side fluid from the compressor islower in the gas turbine power generator of this embodiment than in theknown gas turbine power generator. Hence, the regenerative heat exchangeamount is greatly increased.

With reference to FIG. 7, a description is now made of the regenerativeheat exchange amount with respect to the power generation load in thegas turbine power generator of this embodiment in comparison with thatin the known gas turbine power generator.

FIG. 7 is an explanatory graph showing the regenerative heat exchangeamount with respect to the power generation load in the gas turbinepower generator according to the first embodiment of the presentinvention. In FIG. 7, the vertical axis represents the regenerative heatexchange amount normalized on condition that the regenerative heatexchange amount at the rated load in the known gas turbine powergenerator is set to 100%, and the horizontal axis represents the powergeneration load normalized with the rated load set to 100%.

A solid line A5 indicates the regenerative heat exchange amount withrespect to the power generation load in the gas turbine power generatorof this embodiment, and a broken line B5 indicates the regenerative heatexchange amount with respect to the power generation load in the knowngas turbine power generator.

At any power generation load, the regenerative heat exchange amount inthe gas turbine power generator of this embodiment is 15% or more largerthan that in the known gas turbine power generator. In the range ofpower generation load not lower than 73%, particularly, the regenerativeheat exchange amount increases with respect to the power generation loadat a greater gradient in the gas turbine power generator of thisembodiment than in the known gas turbine power generator. The reason isthat, in addition to an increase of the capacity of the regenerativeheat exchanger, the intake air is in the saturation state at the inletof the regenerative heat exchanger as a result of the humidification onthe delivery side of the compressor, whereby the humidified intake airhas the specific heat and the heat transfer rate larger than those ofnot-humidified air, and the regenerative heat exchanger inlettemperature is reduced to provide a larger temperature differencebetween the inlet and the outlet of the regenerative heat exchanger.

With reference to FIG. 8, a description is now made of the powergeneration efficiency with respect to the power generation load in thegas turbine power generator of this embodiment in comparison with thatin the known gas turbine power generator.

FIG. 8 is an explanatory graph showing the power generation efficiencywith respect to the power generation load in the gas turbine powergenerator according to the first embodiment of the present invention. InFIG. 8, the vertical axis represents the power generation efficiencynormalized on condition that the power generation efficiency at therated load in the known gas turbine power generator is set to 100%, andthe horizontal axis represents the power generation load normalized withthe rated load set to 100%.

A solid line A6 indicates the power generation efficiency with respectto the power generation load in the gas turbine power generator of thisembodiment, and a broken line B6 indicates the power generationefficiency with respect to the power generation load in the known gasturbine power generator.

At any power generation load, the power generation efficiency is higherin the gas turbine power generator of this embodiment than in the knowngas turbine power generator. Also, while the power generation efficiencyin the known gas turbine power generator reduces as the power generationload decreases, the power generation efficiency in the gas turbine powergenerator of this embodiment moderately increases in the range of powergeneration load from 100% to 90% and is substantially constant in therange of the power generation load not larger than 90%.

Such a moderate increase of the power generation efficiency in the rangeof power generation load from 100% to 90% is attributable to that theoperation state following the power generation load is achieved just byregulating the flow rate Mw of the humidifying water in the state inwhich it exceeds the optimum flow rate MOpw of the humidifying water,and the flow rate Mw of the humidifying water becomes closer to theoptimum flow rate MOpw as the load decreases.

With reference to FIG. 9, a description is now made of the number ofrotations with respect to the power generation load in the gas turbinepower generator of this embodiment in comparison with that in the knowngas turbine power generator.

FIG. 9 is an explanatory graph showing the number of rotations withrespect to the power generation load in the gas turbine power generatoraccording to the first embodiment of the present invention. In FIG. 9,the vertical axis represents the number of rotations normalized oncondition that the number of rotations at the rated load is set to 100%,and the horizontal axis represents the power generation load normalizedwith the rated load set to 100%.

A solid line A7 indicates the number of rotations with respect to thepower generation load in the gas turbine power generator of thisembodiment, and a broken line B7 indicates the number of rotations withrespect to the power generation load in the known gas turbine powergenerator.

As is apparent from FIG. 9, in the range of power generation load from100% to 90%, the number of rotations of the gas turbine power generatorof this embodiment is held at the rated number of rotations and does notvary. In addition, a variation width of the number of rotations in therange of power generation load from, e.g., 50% to the rated load is alsosmall. Thus, with the operation control theory according to thisembodiment, the frequency of variation in the number of rotations can bereduced as compared with that in the prior art, and high-cycle thermalfatigue of the turbine can be suppressed so as to prolong the servicelife of the gas turbine power generator of this embodiment.

With this embodiment, as described above, it is possible to increase thepower generation efficiency in the partial load operation and todecrease a variation in the number of rotations caused by a variation inthe power generation load.

Next, the construction and operation of a gas turbine power generatoraccording to a second embodiment of the present invention will bedescribed below with reference to FIG. 10. The overall construction ofthe gas turbine power generator according to this embodiment is the sameas that shown in FIG. 1.

The following description is therefore made of a method of operating thegas turbine power generator according to this embodiment with referenceto FIG. 10.

FIG. 10 is a flowchart showing the method of operating the gas turbinepower generator according to the second embodiment of the presentinvention. In control flows shown in the flowchart, (A) in FIG. 10continues to (A) in FIG. 3 and (B), (C) in FIG. 10 continue respectivelyto (B), (C) in FIG. 4. Additionally, the same step numbers as those inFIGS. 2 to 4 represent the same control procedures.

Since basic control procedures of the operating method are the same asthose shown in FIGS. 2 to 4, a description is made primarily ofdifferent points in comparison with FIGS. 2 to 4. In this embodiment,processing of step s209 is executed instead of step s203 shown in FIG.2.

In step s209, the control unit 100 compares intake-air specific heatC_(P) at the inlet of the regenerative heat exchanger with intake-airspecific heat C_(PT) in the saturation state. As a result of comparingthe intake-air specific heat C_(P) with the intake-air specific heatC_(PT) in the saturation state, if the intake-air specific heat C_(P) islarger than the intake-air specific heat C_(PT) in the saturation state(C_(P)>C_(PT)), the control unit 100 issues, in step s204, the commandfor decreasing the flow rate Mw of the humidifying water. If theintake-air specific heat C_(P) is not larger than the intake-airspecific heat C_(PT) in the saturation state (C_(P)≦C_(PT)), the controlunit 100 issues, in step s119, the command for decreasing the number ofrotations N.

Here, the intake-air specific heat C_(P) is decided from the followingintake-air specific heat calculation formula (1) derived on conditionthat the heat exchange amount on the compressor delivery air side andthe heat exchange amount on the turbine exhaust gas side are equal toeach other for the regenerative heat exchanger 4;C _(P) =C _(PG)(M _(A) +M _(F) /M _(A))((T _(OT) −T _(EX)/(T _(RO) −T_(RI))  (1)

where C_(P): intake-air specific heat, C_(PG): fuel gas specific heat,M_(A): air flow rate, M_(F): fuel flow rate, T_(RI): regenerative heatexchanger inlet temperature, T_(RO): regenerative heat exchanger outlettemperature, T_(OT): turbine outlet temperature, and T_(EX): exhausttemperature.

The intake-air specific heat C_(PT) in the saturation state can bedecided by determining the saturation water vapor temperature using asaturation-water-vapor temperature calculation formula from the pressureand temperature of the intake air on the delivery side of the compressor2, and by employing a specific heat calculation formula for a gasmixture from the water vapor specific heat and the water vapor partialpressure in that condition, as well as from the pressure and specificheat of the intake air on the delivery side of the compressor 2. As analternative, values of the intake-air specific heat C_(PT) in thesaturation state with respect to pressure and temperature over rangespossibly occurred on the delivery side of the compressor may be storedas memory data in a lookup table 210 beforehand and used when decidingthe intake-air specific heat C_(PT) in the saturation state. Further,instead of measuring the pressure and temperature at the inlet of theregenerative heat exchanger, the pressure and temperature at the inletof the regenerative heat exchanger may be calculated by measuring theintake-air flow rate and the pressure and temperature at the inlet ofthe compressor, and determining the compressor efficiency andcompression ratio from a measured value of the number of rotations N anda performance curve approximation formula for the compressor.

In practical use, for example, when the gas turbine power generator ofthis embodiment is coupled to a line system or when it is used incombination with an electricity storage plant, the gas turbine powergenerator is not always required to satisfy all of the load demand byitself alone because deficiency of the load terminal output power P_(GO)with respect to the demanded load power P_(D) can be compensated bypurchasing power from the line system or by supplying power from theelectricity storage plant. In that case, it is also possible to employ amethod of determining respective values of a target flow rate MwT of thehumidifying water, the target number of rotations N_(T) and a targetfuel flow rate M_(FT) which are required to realize the operation statesatisfying the load demand and maximizing the power generationefficiency, and carrying out steady operation with the determined valuesset to control target values. The respective values of the target flowrate MwT of the humidifying water, the target number of rotations N_(T)and the target fuel flow rate M_(FT) can be determined, for example, bycalculating respective values of the intake-air specific heat C_(P), theair flow rate M_(A) and the fuel flow rate M_(F) at which theregenerative heat exchanger outlet temperature T_(RO) in the right sideof the formula (1) is maximized.

Thus, this embodiment can eliminate the necessity of changing thecontrol target values depending on the operation state, and can minimizea variation in the number of rotations. In some cases, however, the loadterminal output power P_(GO) may become insufficient with respect to thedemanded load power P_(D) until the operation state reaches the steadycondition.

With this embodiment, as described above, it is possible to increase thepower generation efficiency in the partial load operation, and todecrease a variation in the number of rotations caused by a variation inthe power generation load. Further, the necessity of changing thecontrol target values depending on the operation state is eliminated,and a variation in the number of rotations can be minimized.

Next, the construction and operation of a gas turbine power generatoraccording to a third embodiment of the present invention will bedescribed below with reference to FIGS. 11 to 13. The overallconstruction of the gas turbine power generator according to thisembodiment is the same as that shown in FIG. 1.

The following description is therefore made of a method of operating thegas turbine power generator according to this embodiment with referenceto FIG. 11.

FIG. 11 is a flowchart showing the method of operating the gas turbinepower generator according to the third embodiment of the presentinvention. In control flows shown in the flowchart, (A) in FIG. 11continues to (A) in FIG. 3 and (B), (C) in FIG. 11 continue respectivelyto (B), (C) in FIG. 4. Additionally, the same step numbers as those inFIG. 10 represent the same control procedures.

Since basic control procedures of the operating method are the same asthose shown in FIG. 10, a description is made primarily of differentpoints in comparison with FIG. 10. In this embodiment, processing ofstep s212 is executed instead of step s209 shown in FIG. 10.

In step s212, the control unit 100 compares a regenerative heatexchanger temperature gradient ΔT_(RO-RI/LR), which is resulted fromdividing a temperature difference ΔT_(RO-RI) between the inlet and theoutlet of the regenerative heat exchanger 4 by a flow passage lengthL_(R) inside the regenerative heat exchanger, with a referencetemperature gradient (ΔT_(RO-RI/LR))T in the regenerative heatexchanger.

As a result of comparing the regenerative heat exchanger temperaturegradient ΔT_(RO-RI/LR) with the reference temperature gradient(ΔT_(RO-RI/LR))T, if the regenerative heat exchanger temperatureΔT_(RO-RI/LR) is lower than the reference temperature gradient(ΔT_(RO-RI/LR)) T ((ΔT_(RO-RI/LR))<((ΔT_(RO-RI/LR)) T)) the control unit100 issues, in step s204, the command for decreasing the flow rate Mw ofthe humidifying water.

If the regenerative heat exchanger temperature gradient ΔT_(RO-RI/LR) isnot lower than the reference temperature gradient (ΔT_(RO-RI/LR))T((ΔT_(RO-RI/LR)) ≧((ΔT_(RO-RI/LR))T)), the control unit 100 issues, instep s119, the command for decreasing the number of rotations N.

Here, the regenerative heat exchanger temperature gradient ΔT_(RO-RI/LR)is decided from measured values of the inlet and outlet temperatures ofthe regenerative heat exchanger 4, and the reference temperaturegradient (ΔT_(RO-RI/LR))T is decided based on a thermal balancecalculation. As an alternative, values of the reference temperaturegradient (ΔT_(RO-RI/LR))T with respect to pressure and temperature atthe inlet of the regenerative heat exchanger over necessary ranges maybe stored as memory data in a lookup table beforehand. Further, insteadof measuring the pressure and temperature at the inlet of theregenerative heat exchanger, the pressure and temperature at the inletof the regenerative heat exchanger may be calculated by measuring theintake-air flow rate and the pressure and temperature at the inlet ofthe compressor, and determining the compressor efficiency andcompression ratio from a measured value of the number of rotations N anda performance curve approximation formula for the compressor.

With reference to FIGS. 12 and 13, a description is now made of atemperature distribution in the regenerative heat exchanger resultingwhen the flow rate Mw of the humidifying water is changed in five waysin the gas turbine power generator according to this embodiment.

FIG. 12 is an explanatory graph showing a temperature distribution inthe regenerative heat exchanger resulting when the flow rate Mw of thehumidifying water is changed in five ways in the gas turbine powergenerator according to the third embodiment of the present invention,and FIG. 13 is an enlarged graph of a portion of FIG. 12. In FIG. 12,the vertical axis represents the temperature in the regenerative heatexchanger, and the horizontal axis represents the position in theregenerative heat exchanger, at which the temperature is measured, afternormalization with the flow passage length in the regenerative heatexchanger set to 100%.

A solid line C1 indicates the case of humidifying the intake air just atthe optimum flow rate MOpw of the humidifying water. A broken line C2indicates the case of humidifying the intake air at the flow rate Mw4 ofthe humidifying water smaller than the optimum flow rate MOpw. Atwo-dot-chain line C3, a one-dot-chain line C4 and a dotted line C5indicate respectively the cases of humidifying the intake air at theflow rates Mw3, Mw2 and Mw1 of the humidifying water larger than theoptimum flow rate MOpw. Those flow rates of the humidifying water meet acondition of Mw4<MOpw<Mw1<Mw2<Mw3.

In the case of humidifying the intake air at the flow rate smaller thanthe optimum flow rate MOpw of the humidifying water (broken line C2),the regenerative heat exchanger temperature gradient ΔT_(RO-RI/LR) islarger than in the case of humidifying the intake air just at theoptimum flow rate MOpw of the humidifying water (solid line C1).

Further, as is apparent from FIG. 11 showing, in enlarged scale, aportion in which the temperature measured position in the regenerativeheat exchanger ranges from 0 to 20%, the cases (two-dot-chain line C3,one-dot-chain line C4 and dotted line C5) of humidifying the intake airat the flow rates larger than the optimum flow rate MOpw of thehumidifying water include a zone in which an effective temperature riseis not obtained until droplets of the humidifying water evaporate. Inthe cases of humidifying the intake air at the flow rates larger thanthe optimum flow rate MOpw of the humidifying water, therefore, theregenerative heat exchanger temperature gradient ΔT_(RO-RI/LR) isreduced.

Additionally, as is apparent from FIGS. 12 and 13, while theregenerative heat exchanger temperature gradient ΔT_(RO-RI/LR) is usedin this embodiment for deciding the optimum flow rate of the humidifyingwater, a temperature gradient in a region the effective temperature risein the regenerative heat exchanger changes may be used instead.

With this embodiment, as described above, it is possible to increase thepower generation efficiency in the partial load operation, and todecrease a variation in the number of rotations caused by a variation inthe power generation load. Further, an optimum regenerative heatexchanger temperature gradient can be obtained by adjusting the flowrate Mw of the humidifying water based on the regenerative heatexchanger temperature gradient ΔT_(RO-RI/LR).

Next, the construction and operation of a gas turbine power generatoraccording to a fourth embodiment of the present invention will bedescribed below with reference to FIG. 14.

FIG. 14 is a system diagram showing an overall construction of the gasturbine power generator according to the fourth embodiment of thepresent invention. Note that the same characters as those in FIG. 1denote the same components.

This embodiment includes neither the intake-air sprayer 1 nor theassociated accessory equipment, which are provided in the gas turbinepower generator shown in FIG. 1. The other construction is the same asthat shown in FIG. 1. Also, a control unit 100A executes operationcontrol in the same manner as that shown in FIGS. 2 to 4. However, theflow rate Mw of the humidifying water is controlled only by thehumidifier 3. Alternatively, the operation control may be executed usingthe same manner as that shown in FIG. 10 or 11.

This embodiment is applicable to, for example, a district where avariation in temperature of open air is small or a district where anannual highest atmospheric temperature is relatively low, and humidifiesthe intake-air by the humidifier 3 alone without employing theintake-air sprayer 1. Because moisture tends to more easily saturate atthe inlet of the compressor 2, the outlet temperature of the compressor2 is reduced by humidifying the intake-air with the humidifier 3 so thateasier humidification is realized and the power generation efficiency isincreased.

With this embodiment, as described above, it is possible to increase thepower generation efficiency in the partial load operation, and todecrease a variation in the number of rotations caused by a variation inthe power generation load.

Next, the construction and operation of a gas turbine power generatoraccording to a fifth embodiment of the present invention will bedescribed below with reference to FIG. 15.

FIG. 15 is a system diagram showing an overall construction of the gasturbine power generator according to the fifth embodiment of the presentinvention. Note that the same characters as those in FIG. 1 denote thesame components.

This embodiment includes neither the humidifier 3 nor the associatedaccessory equipment, which are provided in the gas turbine powergenerator shown in FIG. 1. The other construction is the same as thatshown in FIG. 1. Also, a control unit 100B executes operation control inthe same manner as that shown in FIGS. 2 to 4. However, the flow rate Mwof the humidifying water is controlled only by the intake-air sprayer 1.Alternatively, the operation control may be executed using the samemanner as that shown in FIG. 10 or 11. Because the temperature of theintake-air flowing into the compressor 2 can be reduced by humidifyingthe intake-air with the intake-air sprayer 1, the compression efficiencyof the compressor 2 is increased and so is the amount of air supplied tothe turbine 6. As a result, the generator output can be increased.

With this embodiment, as described above, it is possible to increase thepower generation efficiency in the partial load operation, and todecrease a variation in the number of rotations caused by a variation inthe power generation load.

Next, the construction and operation of a gas turbine power generatoraccording to a sixth embodiment of the present invention will bedescribed below with reference to FIGS. 16 and 17.

FIG. 16 is a system diagram showing an overall construction of the gasturbine power generator according to the sixth embodiment of the presentinvention. Note that the same characters as those in FIG. 1 denote thesame components.

This embodiment includes a regenerative-heat-exchanger inner temperaturemeasuring means 45 capable of measuring temperatures inside theregenerative heat exchanger 4 at multiple points.

A method of operating the gas turbine power generator according to thisembodiment will be described below with reference to FIG. 17.

FIG. 17 is a flowchart showing the method of operating the gas turbinepower generator according to the sixth embodiment of the presentinvention. In control flows shown in the flowchart, (A) in FIG. 17continues to (A) in FIG. 3 and (B), (C) in FIG. 17 continue respectivelyto (B), (C) in FIG. 4. Additionally, the same step numbers as those inFIG. 2 represent the same control procedures.

Since basic control procedures of the operating method are the same asthose shown in FIG. 2, a description is made primarily of differentpoints in comparison with FIG. 2. In this embodiment, processing of steps214 is executed instead of step s118 shown in FIG. 2, and processing ofstep s118 is executed instead of step s203 shown in FIG. 2.

If the turbine outlet temperature T_(OT) is lower than the turbineoutlet setting temperature T_(OTT), a control unit 100C compares atemperature T_(RM1) inside the regenerative heat exchanger at a positionclosest to the inlet with the regenerative heat exchanger inlettemperature T_(RI) in step s214.

As a result of the comparison, if the temperature T_(RM1) inside theregenerative heat exchanger at the position closest to the inlet isequal to the regenerative heat exchanger inlet temperature T_(RI)(T_(RM1)=T_(RI)), the control unit 100C issues the command fordecreasing the flow rate Mw of the humidifying water in step s204.

If the temperature T_(RM1) inside the regenerative heat exchanger at theposition closest to the inlet is higher than the regenerative heatexchanger inlet temperature T_(RI) (T_(RM1)>T_(RI)), the control unit100C compares the regenerative heat exchanger outlet temperature T_(RO)with the regenerative-heat-exchanger inlet setting temperature T_(ROT)in step s118.

As a result of comparing the regenerative heat exchanger outlettemperature T_(RO) with the regenerative-heat-exchanger outlet settingtemperature T_(ROT), if the regenerative heat exchanger outlettemperature T_(RO) is not lower than the regenerative-heat-exchangerinlet setting temperature T_(ROT) (T_(RO)≧T_(ROT)), the control unit100C issues the command for exiting the optimization loop in step s115.Then, in step s202, the control unit 100C issues the command for holdingthe flow rate Mw of the humidifying water and the number of rotations Nat the same values as those set at that time.

If the regenerative heat exchanger outlet temperature T_(RO) is lowerthan the regenerative-heat-exchanger inlet setting temperature T_(ROT)in (T_(RO)<T_(ROT)), the control unit 100C issues the command fordecreasing the number of rotations N in step s119.

With this embodiment, as described above, it is possible to increase thepower generation efficiency in the partial load operation, and todecrease a variation in the number of rotations caused by a variation inthe power generation load.

In each of the embodiments described above, since cooled water issupplied to the intake-air sprayer 1 through the intake-air coolingwater ejection pump 34 and the intake-air is humidified and cooled withthe intake-air spraying water 25, the power required for the compressorcan be reduced and the power generation terminal output and the powergeneration efficiency can be increased.

Even with a very small flow rate of about 0.01 weight percent of the airmass flow rate, the intake-air spraying water 25 is effective inreducing the compressor power through change in the specific heat ratioresulting from the humidification. In order to positively evaporate theintake-air spraying water and quickly humidify the intake air, however,a flow rate of about 0.4 weight percent of the air mass flow rate isappropriate. In this respect, among droplets of the intake-air sprayingwater which did not evaporate, large-sized droplets are discharged andrecovered as the drained water 28, while small-sized droplets aredelivered from the compressor together with the intake air and thenevaporate on the delivery side of the compressor, thereby developing asimilar effect to that obtainable with the case of slightly humidifyingthe intake air by the humidifier 3.

When carrying out spray cooling of the intake air, therefore, the flowrate set in step s201 by multiplying the air flow rate M_(A) by theconstant α is set to a value that is resulted from reducing the amountof the drained water per unit time from the flow rate of the intake-airspraying water.

INDUSTRIAL APPLICABILITY

According to the present invention, it is possible to increase the powergeneration efficiency in the partial load operation, and to decrease avariation in the number of rotations caused by a variation in the powergeneration load.

What is claimed is:
 1. A gas turbine power generator comprising: acompressor for compressing air; a combustor for burning the compressedair and fuel; a turbine driven by combustion gas produced in saidcombustor and driving said compressor and a generator; a regenerativeheat exchanger for exchanging heat between exhaust gas from said turbineand the compressed air led into said combustor; humidifying and coolingmeans for humidifying and cooling intake air flown into saidregenerative heat exchanger, and control means for controlling a flowrate of humidifying water supplied by said humidifying and cooling meansto a value required for making an intake air temperature at an inlet ofsaid regenerative heat exchanger coincident with a saturation watervapor temperature.
 2. A gas turbine power generator according to claim1, wherein said humidifying and cooling means is an intake air sprayerfor spraying water to the intake air at an inlet of said compressor,thereby humidifying and cooling the intake air led into said compressor.3. A gas turbine power generator according to claim 1, wherein saidhumidifying and cooling means is a humidifier for spraying water to aircompressed by said compressor.
 4. A gas turbine power generatoraccording to claim 1, wherein said control means controls the number ofrotations of said turbine and a flow rate of fuel supplied to saidcombustor.
 5. A gas turbine power generator according to claim 4,wherein said control means controls the flow rate of the humidifyingwater to be coincident with an optimum flow rate of the humidifyingwater as far as possible, thereby reducing the number of times at whichthe number of rotations is adjusted.
 6. A gas turbine power generatoraccording to claim 5, wherein said control means decides the optimumflow rate (MOPW) of the humidifying water by comparing a temperaturegradient, which is resulted from dividing a temperature differencebetween an inlet and an outlet of said regenerative heat exchanger by aflow passage length inside said regenerative heat exchanger, with atarget temperature gradient in said regenerative heat exchanger.
 7. Agas turbine power generator according to claim 4, wherein said controlmeans makes control, after setting the flow rate of the humidifyingwater on the delivery side of said compressor to a maximum setting flowrate, to gradually reduce the flow rate of the humidifying water to anoptimum flow rate of the humidifying water while confirming that anoutlet temperature of said regenerative heat exchanger and an inlet oroutlet temperature of said turbine are lower than respective settingtemperatures.
 8. A gas turbine power generator according to claim 7,wherein said control means decides the optimum flow rate (MOPW) of thehumidifying water by measuring a pressure and temperature at an inlet ofsaid regenerative heat exchanger, and employing a saturation temperatureformula.
 9. A gas turbine power generator according to claim 7, whereinsaid control means decides the optimum flow rate (MOPW) of thehumidifying water by comparing the specific heat of the intake air at aninlet of said regenerative heat exchanger with the specific heat of theintake air in a saturation state.
 10. A gas turbine power generatoraccording to claim 7, wherein said control means decides the optimumflow rate (MOPW) of the humidifying water by measuring an inlettemperature said regenerative heat exchanger and an air temperatureinside said regenerative heat exchanger.
 11. A gas turbine powergenerator according to claim 4, wherein when an inlet temperature or anoutlet temperature of said turbine rises excessively, said control meansincreases the flow rate of the humidifying water to lower the inlettemperature or the outlet temperature of said turbine for return to asafe operation state.
 12. A gas turbine power generator according toclaim 4, wherein when decreasing the flow rate Mw of the humidifyingwater on the delivery side of said compressor, said control means sets adecrease amount of the humidifying water to the least possible valuewithin the flow rate adjustable range.
 13. A gas turbine power generatoraccording to claim 4, wherein said control means issues an alarm whentemperatures of said combustor and said turbine exceeds alarm settingtemperatures, and sets the alarm setting temperatures to higher valuesdepending on a rise of the open air temperature.